Cellulosic textile fibers bearing grafted n-methylol amide



United States Patent 3,423,163 CELLULOSIC TEXTILE FIBERS BEARING GRAFTEDN -METHYLOL AMIDE Eugene Edward Magat, Wilmington, Del., and DavidTanner, Chariottesville, Va., assignors to E. I. du Pont de Nemours andCompany, Wilmington, Del., a corporation of Delaware No Drawing.Original application June 3, 1959, Ser. No. 817,881. Divided and thisapplication July 19, 1966, Ser. No. 566,258

US. Cl. 8-1163 2 Claims Int. Cl. Dtldm 13/40 ABSTRACT OF THE DISCLOSUREA cellulosic textile fiber bearing polymeric chains grafted to thecellulosic fiber, the said chains being derived from an N-met'hylolamide of an unsaturated acid, said chains being grafted to saidcellulosic fiber via carbon-tocarbon bonds in which one of the carbonsof the bond is a cellulosic carbon. Among the fibers exemplified arecotton and rayon grafted with N-methylol-acrylamide.

This application is a division of United States application 817,881,filed June 3, 1959, now abandoned, which was a continuation-in-part ofUnited States applications Nos. 500,032, filed Apr. 7, 1955, and nowabandoned, and 503,792, filed Apr. 25, 1955, and now abandoned.

This invention relates to cellulosic textile fibers having graftedthereto an organic compound.

The fibers of nature, i.e., those from natural carbonaceous cellulose,protein and isoprene polymers have many deficiencies when employed forapparel purposes. Attempts to cure these deficiencies by surfacetreatments with resins, etc., have not been satisfactory. For example,thin resin coatings on the filaments are not permanent to laundering.Heavy deposits of resins, rendered more durable and self-supporting bycross-linking, stiffen the fabric, making it harsh and unpleasant tohandle or wear. Carried to an extreme, the fabric becomes bonded into astiff unitary structure lacking in aesthetic appeal and good wearproperties.

OBJECT An object of this invention is to provide a textile formed from anatural carbonaceous polymer which is permanently modified to make it,for instance, more free from static, more dyeable, more resilient orcrease resistant or more flame resistant, than textiles heretoforeobtainable from the said polymers. Products having moisture absorption,hand and strength characteristics differing from the naturalcounterparts are also provided.

This and other objects will become apparent in the course of thefollowing specification and claims.

STATEMENT OF INVENTION The fibers of this invention are described ascellulosic textile fibers bearing polymeric chains grafted to thecellulosic fibers. the said chains being derived from an N-methylolamide of an unsaturated acid, said chains being grafted to saidcellulosic fibers via carbon-to-carbon bonds in which one of the carbonsof the bond is a cellulosic carbon.

DEFINITIONS By the term textile produced from. a fiber-foamingcarbonaceous material of nature is meant a structure produced fromfilaments or films having a cellulose, protein or isoprene polymericcomposition and formed in plant or animal growth and to fiberandfilm-forming derivatives and regenerated forms of the naturalcarbonaceous "ice polymers such as protein, cellulose acetate andregenerated cellulose.

By graft copolymer is meant a polymer which is modified, after shaping,by chemically bonding thereto, molecules of a chemically dissimilarorganic compound.

By irradiation is meant the process by which energy is propagatedthrough space, the possibility of propagation being unconditioned by thepresence of matter (as distinguished from mere mechanical agitation in amaterial medium such as is characteristic of energy produced by a sonicor ultrasonic transducer), although the speed, direction, and amount ofenergy transferred may be thus affected.

By ionizing radiation is meant radiation with sutficient energy toremove an electron from a gas atom, forming an ion pair; this requiresan energy of about 32 electron volts (ev.) for each ion pair formed.This radiation has sufficient energy to nonselectively break chemicalbonds; thus, in round numbers radiation with energy of about 50 electronvolts (ev.) and above is effective for the process of this invention.The ionizing radiation of this process of this invention is generallyclassed in two types: high energy particle radiation, and ionizingelectromagnetic radiation. The effect produced by these two types ofradiation is similar, the essential requisite being that the in cidentparticle or photons have sufficient energy to break chemical bond andgenerate free radicals.

The preferred radiation for the practice of this invention is highenergy ionizing radiation, and has an energy equivalent to at least 0.1million electron volt (anew). Higher energies are even more effective;there is no known upper limit, except that imposed by availableequipment.

EXPERIMENTAL PROCEDURES AND UNITS Compositions are given in parts byweight or weight percent, unless otherwise noted.

Radiation dosages are given in units of mrad (millions of rads), a radbeing the amount of high energy radiation of any type Wich results in anenergy absorption of ergs per gram of Water or equivalent absorbingmaterial. Alternatively, dosages may be indicated in terms of exposurein watt seconds per square centimeter of substrate treated.

The standard washing to which samples are subjected consists of a30-minute immersion in 18 liters of 70 C. water contained in a 20-literagitation washer. T he wash solution contains 0.5% of detergent. Thedetergent employed is that sold under the trademark Tide. This detergentcontains, in addition to the active ingredient, well over 50% (sodium)phosphates (Chemical Industries, 60, 942, July, 1947). Analysis showsthe composition to be substantially as follows:

Percent Sodium lauryl sulfate l6 Alkyl alcohol sulfate 6 Sodiumpolyphosphate 30 Sodium pyrophosphate 17 Sodium silicates and sodiumsulfate 31 The static propensity of the fabric is indicated in terms ofdirect current resistance in ohms per square, measured parallel to thefabric surface, at 78 F. in a 50% relative humidity atmosphere. Highvalues, reported as the logarithm (to the base 10) of the resistivity(log R) indicate a tendency to acquire and retain a static charge. Ameter suitable for this determination is described by Hayek and Chromey,American Dyestuff Reporter, 40, 225 (1951).

Crease recovery is evaluated by cnumipling a fabric in the hand, andobserving the rate at which it recovers from this treatment. Numericalvalues are obtained using the vertical strip crease recovery testdescribed in the American Society for Testing Materials Manual, Test No.D1295-53T. In determining crease recovery by this method, the specimensare creased under a standard weight; the weight is then removed, and therecovery after 300 seconds is measured, averaging results obtained inthe filling and warp directions.

The following examples are cited to illustrate the invention. They arenot intended to limit it in any manner.

When a Van de Graaif generator is used for the irradiation treatment,the following conditions are typical:

Voltage-mev. 2

Tube current, microamperes 290 Conveyor speed, in./min. 40

Dose per pass, mrad 2 Example I Pieces of scrubbed cotton sheeting (80 x80 count) and scrubbed rayon challis are immersed in aqueous solutionsof N-methylol acrylamide (MAA) at room temperature, and squeezed betweenrubber rolls to remove excess solution. The soaking and squeezing arerepeated. The amount of N-methylol acrylamide padded on the fabrics iscalculated from the wet-pickup and the pad bath concentration. A fewfabrics are sealed in polyethylene bags while wet but in most casesfabrics are air-dried prior to sealing. The fabrics in polyethylene bagsare exposed at about 25 C. to ,B-radiation from the 2 mev. vertical Vande Graaif electrostatic generator. After irradiation the fabrics arerinsed several times in distilled Water, in water containing 0.2%Duponol ME 1 at 50 C. for 30 minutes, and finally in distilled water.The amounts of MAA grafted are determined by weight gains (dried at 110C. for 1 hour) or from microKjeldahl nitrogen analyses.

The data are summarized in Table 1 below:

TABLE 1 Percent Radiated Radiation Sample Fabric MAA in wet or dose,Percent pad bath dry mrad gain 10. 3 W' l5 l4. 2

10 D 2 ll. 4

To develop improved crease recovery and resilience (fabric |bounce), thefabrics containing grafted N- methylol acrylamide are soaked in a onepercent aqueous solution of tartaric acid and squeezed between rubberrolls. Fabrics are cured, after air drying, at 160 C. for minutes, andare then rinsed well in distilled water. Crease recovery and tensilestrength data are summarized in the following table. Data fromconventional dimethylol ethylene urea (DMEU) treatment are included forcomparison.

Comparisons of cotton fabric properties produced by curing graftedN-methylol acrylamide (MAA) fabrics and dimethylol ethylene urea (DMEU)applied in the conventional way are given in Table 3, ratedsubjectively.

The sodium salt of technical lauryl alcohol sulfate.

TABLE 3 Vertical strip Fabric Stability Sample Cotton crease bounce toacid* angle (degrees) Untreated Poor 101 (4% wt. 250 Good... Poor.

gain 10B MAA (4.9% wt. 251 Very good--- Good.

gain).

*Acid stability of finish estimated by boiling in 0.2% acetic acid andthen comparing swelling and solubility of fibers in cuprammoniasolution.

It is apparent that at approximately the same weight gain, the fabicstreated in accordance with this invention not only have crease recoveryequivalent to conventional dimethylol ethylene urea treatments, but showimproved fabric bounce or resilience, as well as improved stability toacid. Increased amounts of grafted, cured N-rnethylol acrylamide givesome additional improvement. The amount of grafted N-methylol acrylamiderequired for improving crease-resistance on cellulosics is about 2 to5%, although as much as 15% can be used.

TEXTILE S UB STRATE As illustrated in the examples, the textile producedfrom the fiber-forming, carbonaceous polymer of nature acts as asubstrate to which the organic compound is bonded by means of radiation.

The textiles treated in accordance with this invention include naturalfibers such as cotton, fiax, jute, hemp, ramie, sisal, abaca, phormium,silk, wool, fur, hair and materials produced from derivative andregenerated forms of natural polymers, such as cellulose acetate,cellulose triacetate, regenerated cellulose, protein fiber derived frompeanut protein, zein, casein and the like. Indeed, film such asregenerated cellulose or natural rubber film may be treated inaccordance with the process of this invention, and thereafter be slit toform fine ribbon-like filaments useful for making fabrics, etc. Theprocess of the present invention may be applied to a funicular structuresuch as a continuous fiber, a filament, a spun yarn, cord, tow, floc,bristle, artificial straw, staple or the like. It may likewise beapplied to a fabric of a woven, knitted, felted or other construction.

The shaped article, where its nature will permit, such as in celluloseacetate, may be in the form of finely comminuted particles which may,after having the organic compound grafted to it, be dissolved and shapedby dry spinning into a fiber. However, since the grafted natural polymermust be soluble or melt-spinnable the versatility of this embodiment ofthe process is limited; thus, it is preferred to perform the graftingoperation on the polymer in its final shape, e.g., in textile form. inthis way, the location of the grafted modification may be controlled,Whether upon the surface, partially penetrating the filament, orcompletely penetrating it, elfecting a bulk modification.

OPERABLE MODIFIERS Any organic compound may be employed as the modifyingmaterial which may be grafted to the textile. Compounds with aliphaticunsaturation are especially preferred since a minimum radiation dose isrequired to graft a given weight of modifier.

UNSATURATED MODIFIERS Among suitable materials are hydrocarbons such asethylene, propylene, styrene, ot-methyl styrene, divinyl benzene,1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2- chloro-2, 3-butadiene,isoprene, cyclopentadiene, chloroprene; acids such as maleic acid,crotonic acid, dichloromaleic acid, furoic acid, acrylic acid,methacrylic acid, undecylenic acid, cinnamic acid; amides such asacrylamide, methacrylamide, N-methylolacrylamide, N-methyl, N-vinylformamide, N-vinyl pyrrolidone, methyl substituted N-vinyl pyrrolidone,vinyl oxyethyl formamide,

methylene-bis-acrylamide, N-allyl-caprolactam; acrylate esters such asmethyl acrylate, ethyl acrylate, benzyl acrylate, octyl acrylate, methylmethacrylate, butyl methacrylate, vinyl acrylate, allyl acrylate,ethylene diacrylate, diallyl itaconate, diethyl maleate,-N,N-diethylaminoethyl methocrylate, dihydroxy dipyrone; nitriles suchas acrylonitrile, methacrylonitrile; acrylyl halides such as acrylylchloride; vinylic alcohols such as allyl alcohol, furfuryl alcohol,3-hydroxycyclopentene, dicyclopentenyl alcohol, tropolone; alde'hydiccompounds such as acrolein, methacrolein, crotonaldehyde, furfural,acrolein diethyl acetal; vinyl amines such as vinyl pyridine, allylamine, diallyl amine, vinyloxyethylamine, 3,3-dimethyl 4dimethylamino-l-butene, N, N diacryltetramethylene diarnine, N,N-diallylmelamine, diamino octadiene; quaternized amines such as tetraallylammonium bromide, vinyl trimethyl ammonium iodide, the quaternarymethiodide of methylene-3-aminometheylcyclobutane; vinyl esters such asvinyl acetate, vinyl salicylate, vinyl stearate, allyl formate, allylacetate, diallyl adipate, diallyl isophthalate; vinyl ethers such asallyl iglycidyl ether, vinyl Z-chloroethyl ether, dihydropyrane, methoxypolyethyleneoxymethacrylate; vinyl halides such as vinyl chloride, vinylfluoride, tetrachloroethylene, tetrafiuoroethylene, 1,1-dichloro-2,2-difluoroethylene, vinylidene chloride, hexachloropropene,hexachlorocyclopentadiene, p-chlorostyrene, 2,5-dichlorostyrene, allylbromide, Z-bromoethyl acrylate, vinyl tetrafluoropropionate,1,1,7-trihydroperfluoroalkylacrylate such as 1,1,7-trihydroperfluoroheptylacrylate; isocyanate type compounds such asvinyl isocyanate, acrylyl isocanate, allyl isothiocyanate; vinyl ketonessuch as methyl vinyl ketone, ethyl vinyl ketone; cyanides such asmethacrylyl cyanide, allyl isocyanide; nitro compounds such as 2-nitropropene, 2-nitro-l-butene; phosphorous containing vinyls such asdiethyl vinyl phosphate, diphenyl vinyl phosphine oxide,1-phenyl-3-phosphacycl0penteue-l-oxide, diallyl benzene phosphonate,potassium vinyl phosphonate, bischloroethyl vinyl phosphonate; alsoincluded are alkyl, aryl, aral'kyl phosphonates, phosphites andphosphonates; sulfur containing vinyls including sulfonates,sulfonamides, sulfones, sulfonyl halides; thiocarboxylates, such asdiallyl sulfide, ethylene sulfonic acid, allyl sulfonic acid, methallylsulfonic acid, styrene sulfonic acid, Z-methylpropene- 1,3-disulfonicacid, also including salts and esters of the sulfonic acids; epoxyvinyls, such as butadiene oxide, glycidyl methacrylate.

Acetylenes such as phenylacetylene, acetylene dicarboxylic acid,propiolic acid, proparigylsuccinic acid, proparagyl alcohol,2-methyl-3-butyn-2-ol, 2,2,3,3-tetrafluo-rocyclobutylvinylethylene andthe like may be used successfull y NONPOLYMERIZABLE MODIFIERS Inaddition to compounds containing ethylenic unsaturation, it has beenfound that compounds can be grafted, according to the process of thisinvention, which are ordinarily regarded as nonpolymerizable. Bynonpolymerizable is meant those compounds, free from aliphaticunsaturation, which do not polymerize by free radical initiation. Due tothe efficiency of the high-energy radiation in producing free radicals,it is theorized that free radicals are produced simultaneously on thepolymer substrates and on the saturated nonpolymerizable compounds,whereupon grafting ensues. The preferred nonpolymerizable compounds arethose which have functional groups which are useful in modifying polymerproperties. Thus, such compounds are included as hydrocarbons, alcohols,acids, ethers, ketones, esters, aldehydes, isocyanates, sulfonates,mercaptans, thioethers, disulfides, nitriles, nitro compounds, amines,amides and halides. Typical of suitable alcohols are the alkanols suchas methanol, ethanol, laurol, the polyols, such as glycerine,pentaerythritol, sorbitol, mannitol, their partial esters and the like.Dialkyl ethers such as dimethyl, diethyl, ethylmethyl and the glycolethers as well as the oxyalkylated ethers of partial esters of thepolyols, such as the polyoxyethylene derivative of a fatty acid partialester of sorbitol are suitable. Oxides such as 1,2-diisobutylene oxideare useful. Mercaptans and thioethers analogous to the above may be usedas may also disulfides of a similar nature. As amines may be mentionedthe alkyl amines such as methyl amine, ethyl amine, hexamethylenediamine and dodecylamine. The amides of these amines formed with acidssuch as formic acid, adipic acid, suberic acid, stearic acid and thelike are useful; alternatively, the acids alone are often desirablemodifiers. Halides within the preferred class include the alkyl halidessuch as chloromethane, chloroform, carbon tetrachloride, chloroethane,chloroethylene, dichlorodifiuoromethane, dodecafluoroheptyl alcohol andsimilar materials.

Of the nonpolymerizable compounds, those organic compounds, the bonds ofwhich are easily broken, as, for instance, chain transfer agents, areparticularly preferred, since larger amounts of modifier are graftedwith a given irradiation dose.

It is, of course, obvious that low molecular weight nonpolymerizablemodifiers are preferred, when it is desirable to have the modifierpenetrate into the polymer substrate, to make a bulk modification. Ithas been observed that modifiers with functional groups which have aswelling effect upon the polymer substrate are usually especiallyeffective in penetrating the substrate.

POLYMERIC MODIFIERS Polymeric modifiers are a preferred class forgrafting to substrates which are in the form of fibers, filaments,fabrics or the like. These modifiers are especially suitable when asurface coating is desired, since it is obvious that their ability topenetrate will be limited. When irradiating these compositions, it isbelieved that the coating is grafted by chemical bonds, probablycarbon-carbon bonds, to the fiber surface. Therefore, the process ofthis invention gives a much more durable coating than those obtainableby prior art processes which require polymerization initiators tocross-link the coating, and depend on mere physical bonds to retain thecoating upon the textile. The polymeric modifiers are especiallyadaptable to the process of this invention, since relatively few bondsare needed to graft each large macromolecule to the fiber surface.

The process of this invention is especially suitable for Washfastmodification of fibers and fabrics, as has been shown by the exampleshereinabove. These advantages are obtained by selecting polymericmodifiers which can be applied in a relatively fluid state, e.g., fromsolution, emulsion or as a melt. Viscosities up to about centipoises maybe employed, but lower Viscosities are preferred. When these conditionsare met the modifier migrates into the yarn bundles so that eachfilament in the fabric is individually coated, and a large excess of themodifier is avoided. Excess amounts of modifier result in a deleteriouseffect on fabric hand, and often render the fabric unfit for appareluse. The preferred polymeric modifiers are those which are soluble ordispersible in aqueous solutions, although other solvents may be used insome cases. However, water is the preferred solvent because of itscheapness, availability, and freedom from hazards. Thus, such polymersare preferred as the polyether glycols, polypropylene ethers, polymericalcohols, polymeric acids, polymeric amines, polymeric amides and thelike. These compounds are useful, for.

example, in increasing moisture regain, antistatic effect, andwickability, even beyond that which is characteristic of naturalpolymers. Alternatively, water repellence can be improved by graftinghydrophobic polymeric materials, usually utilizing a solvent other thanwater. Examples of such hydrophobic polymers arepolytetrafluoroethylene, polyvinyl chloride, polymeric esters and thelike.

REACTION CONDITIONS Once free radicals are produced on the carbon atomsof the polymer chain in the presence of a vinyl monomer,

vinyl polymerization is initiated, and polyvinyl chains grow from theinitiating site.

Magat et al. in U.S. Patent No. 3,188,228, dated June 8, 1965, gives ageneral discussion of the structure of a graft copolymer product,effective radiation, radiation energy, radiation dose reactionconditions and irradiation conditions.

Prior to treatment, the textile may be oriented by hot or cold drawing.It may contain additives such as pigments, antioxidants, fillers,polymerization catalysts and the like. After the irradiation, theproduct may be after-treated. Frequently a certain amount of homopolymerformation occurs at the surface which is readily removed by solventextraction or Washing. This treatment is usually preferred. In other aftertreatments, the shaped article may be dyed, bleached, hot or colddrawn, chemically recated, or given coatings of lubricants, sizes or thelike or other similar treatments.

UTILITY The process of the present invention is valuable in creatingboth surface and bulk effects upon textiles produced from carbonaceousnatural polymers. It may be employed upon textiles to affect softness,resilence, tendency to shrink, static propensity, resistance tohole-melting, pilling, hydrophilicity, Wickability, and the like. It isuseful in changing such properties as tenacity, elongation, modulus,creep, compliance ratio, work recovery, tensile recovery, decay ofstress, Wet properties, high-temperature properties, abrasion and wearresistance, moisture regain, fiex life, hydrolytic stability,heat-setting properties, boiloff shrinkage, dry-cleaning properties,heat stability, light durability, zero strength temperature, meltingpoint, soilability, ease of soil removal, laundering properties, Wash-Wear properties, liveliness, crease resistance, crease recovery,torsional properties, hysteresis properties, fiber friction, dyeability(depth, rate, permanence and uniformity), printability, Washfastness ofdyes or finishing treatments (resins, ultraviolet absorbers, etc.),handle and drape properties (stiffening or softening), heat-yellowing,snag resistance, elasticity, density, ease in textile processability,solubility (insolubilization or increase in solubility), bleachability,surface reactivity, delustering action, drying properties, fabric life,crimpability, stretchability, fabric stabilization, compressionalresilience (rugs), thermal and electrical conductivity, transparency,light transmittance, air and Water permeability, fabric comfort, feltingion exchange properties, germicidal properties, adhesion, overallappearance and combinations of these as well as others.

It is apparent that those properties which are not primarily a functionof surface characteristics of the filament (e.g., tenacity, elongation,modulus, and the like) may be more conveniently modified by usingmodifiers which penetrate the filaments prior to irradiation-grafting,thus producing a graft copolymer extending throughout the penetratedvolume. It is also apparent that at times it may be desirable to allowone or more modifiers to penetrate the filaments, and coat one or moremodifiers on the surface of the filaments, then initiate graftingsimultaneously by irradiating them.

Although the invention has been described in terms of treatingfilamentary structures in the form of yarn or Woven or knitted fabric,the process is applicable to fabricated textiles for clothing orindustrial use, reinforcement for composite structures (such as cordsfor mechanical rubber goods, fiber for laminates, etc.), bristle orartificial straw, and the like.

Many other modifications will be apparent to those skilled in the artfrom a reading of the above description Without a departure from theinventive concept.

What is claimed is:

1. A cellulosic textile fiber bearing polymeric chains grafted to thecellulosic fiber, the said chains being derived from an N-methylol amideof an unsaturated acid, said chains being grafted to said cellulosicfiber via carbon-tocarbon bonds in which one of the carbons of the bondis a cellulosic carbon.

2. The textile fiber of claim 1 in which the amide is N-methylolacrylamide.

References Cited UNITED STATES PATENTS 2,173,005 9/1939 Strain 260722,837,511 6/1958 Mantell 260231 3,125,405 3/1964 Gardon n 26017.4

WILLIAM H. SHORT, Primary Examiner.

E. NIELSEN, Assistant Examiner.

U.S. Cl. X.R.

ll7-l39.4, 143; 204-154; 26017, 4, 117.4, 8, 879

